On February 26, 1935, Nazi Germany's ultra-modern air force--the Luftwaffe--is secretly organized under the direction of Hermann Goering. The Versailles Treaty prohibited military aviation in Germany, but the civilian airline Lufthansa allowed flight training for the men who later became Luftwaffe pilots. After seizing power in 1933, Nazi leader Adolf Hitler began to secretly develop his military air force. In February 1935, the Luftwaffe was formally organized, and in March, Hitler revealed it to the world. Two years later, a stinging sample of Germany's new air power was felt in the brutal bombing of Guernica during the Spanish Civil War. After September 1939, Poland, France, and especially Britain and Russia discovered the Luftwaffe to be the deadliest of Germany's armed forces. Britain's Royal Air Force, although outnumbered 2 to 1, handed the Luftwaffe its first defeat in the Battle of Britain. Later in the war, American forces joined the RAF in the battle for Europe's skies, and the once-proud Luftwaffe was destroyed.